Alan W. Heston (October 18, 1934–October 25, 2024): In Memoriam
悼念艾伦·W·赫斯顿，回顾他在国际比较项目（ICP）和宾大世界表（PWT）中的开创性贡献，这些工作使学者和公众能方便地比较各国生活水平和实际收入。
It is with deep sadness we inform the readers of the Review and the general membership of the Association of the passing of Alan W. Heston, Emeritus Professor of Economics and South Asian History at the University of Pennsylvania. He was an active member of the IARIW, served on the Council from 1983 to 1987, was President during 1987–1989, and served on the Editorial Board of the Review. Alan W. Heston will be remembered for his outstanding contributions to our understanding of differences in living standards across countries. Today, these contributions can be recognized in two distinct outcomes. First was his pioneering role in developing the International Comparison Program (ICP) for compiling purchasing power parities (PPPs) of currencies and comparisons of real expenditures across countries. Second were his intellectual contributions and visionary work on constructing panels of PPPs and real incomes, disseminated through the Penn World Table (PWT). The ease with which scholars, students, and journalists alike can look up how, for example, China's average income level compares to that in the United States is in no small part due to Alan's pioneering work. After obtaining his PhD from Yale University in 1962, Alan joined both the Department of Economics and the Department of South Asia Studies at the University of Pennsylvania. Alan was the last surviving member of the distinguished research team, including Professors Irving Kravis (1917–1992) and Robert Summers (1922–2012), who established the ICP at the University of Pennsylvania, in collaboration with the United Nations Statistical Office in 1968. After his pioneering work with Milton Gilbert on international price comparisons, Kravis had the vision to include countries from around the world. Alan joined the project in 1968 and Robert Summers in 1970. While Summers brought his econometric and statistical expertise, Alan complemented Kravis and Summers with his background in development economics, his deep understanding of economies in South Asia, including India, and his appreciation of problems inherent in price comparisons between low- and high-income countries. Reading some of the early ICP studies (Kravis, Heston and Summers, 1982) is a good way to be humbled as a modern-day scholar. It is clear that Alan and his co-authors had a fundamental grasp of the challenges of international income comparisons that continue to vex statisticians to this day. This notably includes how to deal with “comparison-resistant” areas of the economy, such as housing, construction, and medical care. Their discussions of these problems and possible steps toward improving measurement remain worthy of attention today, see Deaton and Heston (2010). Alan played a key role in the initial development and implementation of the framework for ICP and contributed to its development and increase in country coverage. After the project moved to the United Nations, he was in charge of implementing Phase IV of the ICP, providing estimates of “real GDP” for 60 countries in 1980. Alan was also Chair of the Technical Advisory Group for the 2005 cycle of ICP, the first round to be coordinated by the ICP Global Office at the World Bank. He navigated ICP through a multitude of technical and implementation issues associated with a regionalized approach. In particular, he developed methods for linking results from different regions for comparison-resistant areas of housing and construction, a problematic area due to different approaches pursued in different areas. It is Alan's Country Aggregation with Volume Redistribution (CAR-volume) method that is currently used in compiling global results on PPPs and real expenditures based on results from different regions. Alan was fortunate to live long enough to see the ICP flourish and grow into a permanent global statistical program now conducted under the auspices of the United Nations Statistical Commission and instituted as a permanent program at the World Bank. Country coverage increased from 10 countries in Phase I to 176 economies of the world in 2021 cycle of the ICP. Alan continued to make significant contributions to ICP through his membership of the Technical Advisory Group until the time of his death. As late as February of this year, Alan was keen to revisit the problem of linking regional results at the elementary level and a suggested improvement over the current approach. His suggestion will be considered at the next meeting of the Group. The Penn World Table represents the second of Heston's enduring legacies. What began as a collaborative effort to extend ICP results to more countries and time periods evolved into an indispensable resource for international comparisons (Summers and Heston, 1988). The landmark paper by Summers and Heston (1991) provided the scholarly foundation for the dataset and became one of the most cited works in economics. PWT proved transformative for multiple research agendas—it became the empirical backbone of the cross-country growth literature (Barro, 1991) and enabled foundational work in development accounting (Hall and Jones, 1999). Alan maintained a degree of ambivalence about some applications of PWT, particularly when researchers failed to appreciate the inherent uncertainties in international comparisons. As he remarked in his memoirs on the literature inspired by Barro (1991): “There followed too many papers testing models of convergence on versions of the PWT” (Heston, 2017, p. 103). Nevertheless, the broad impact of their work led to recognition from the profession on the fundamental importance of this work. Heston and Summers were named Distinguished Fellows of the American Economic Association in 1998 for their contributions to PWT. Starting in 2010, Alan helped orchestrate the transition of PWT to the Groningen Growth and Development Centre, where the release of version 8.0 marked the first edition of the Penn World Table without direct involvement of Penn scholars, in 2013 (Feenstra, Inklaar and Timmer, 2015). As a researcher, Heston was known for his meticulous attention to data quality and willingness to extensively puzzle over measurement and methodological challenges. The documentation of PWT 7.0 (Heston and Aten, 2011) illustrates this characteristic approach—it shows him carefully working through the complex issue of adjusting China's price level data from 11 cities to better represent national prices, weighing multiple approaches and data sources before arriving at what he deemed a “conservative” adjustment. This kind of careful consideration of data limitations and tireless effort to improve measurement was a hallmark of his scholarly approach. His intellectual journey, particularly in later years, was shared with his wife, Bettina Aten, who made her own substantive contributions to the Penn World Table, as well as to spatial price measurement and regional applications of PPP approaches through her work at the Bureau of Economic Analysis (Aten, 2017). Their efforts, including joint work (Aten and Heston, 2020) advanced our understanding of both international and intra-national price comparisons. With Alan's passing the economics profession has lost an intellectual giant, and those who were fortunate enough to have interacted with him have lost a mentor, a good friend, and an incredible host. He leaves behind his wife, Bettina, and a family from his first marriage of two children, five grandchildren, and two great-grandchildren.